class_docstr: This `Field` represents a list of string tokens.  Before constructing this object, you need
  to tokenize raw strings using a :class:`~allennlp.data.tokenizers.tokenizer.Tokenizer`.
  
  Because string tokens can be represented as indexed arrays in a number of ways, we also take a
  dictionary of :class:`~allennlp.data.token_indexers.token_indexer.TokenIndexer`
  objects that will be used to convert the tokens into indices.
  Each `TokenIndexer` could represent each token as a single ID, or a list of character IDs, or
  something else.
  
  This field will get converted into a dictionary of arrays, one for each `TokenIndexer`.  A
  `SingleIdTokenIndexer` produces an array of shape (num_tokens,), while a
  `TokenCharactersIndexer` produces an array of shape (num_tokens, num_characters).
code: def empty_field(self):
      text_field = TextField([], self._token_indexers)
      text_field._indexed_tokens = {}
      if self._token_indexers is not None:
          for indexer_name, indexer in self.token_indexers.items():
              text_field._indexed_tokens[
                  indexer_name
              ] = indexer.get_empty_token_list()
      return text_field
  
imports: from collections import defaultdict
  from copy import deepcopy
  from typing import Dict, List, Optional, Iterator
  import textwrap
  from spacy.tokens import Token
  import torch
  from allennlp.common.checks import ConfigurationError
  from allennlp.data.fields.sequence_field import SequenceField
  from allennlp.data.tokenizers import Token
  from allennlp.data.token_indexers.token_indexer import TokenIndexer, IndexedTokenList
  from allennlp.data.vocabulary import Vocabulary
  from allennlp.nn import util
label_desc: Use image node_id 9 for calling the TextField obj's underlying member method code with example usage: obj.empty_field() and returns: text_field